DANGERS OF 3 PELLET LOADS

As promised, this thread is dedicated to showing how pressures in the breech translate into stress in the barrel. Again lets consider the 25-06. A glance at the barrel and it is obviously wider at the breech than at the muzzle. This of course isbecause pressures are higher near the breech than at the muzzle.

When the powder is ignited, pressure in the breech, impresses force on the inner surface of the barrel, which must be born by the elastic properties of the barrel. The barrel expands straining the metal within it until sufficient stress is born by the barrel to completely and totally offset the forces on the barrel's inner surface. This is an action - equal reaction of the Newton type.

We know that the force related to thestressin the metalof the barrel is equal and opposite to the force impressed by the charge on the barrels inner surface. So if we know the dimensions of the barrel and the pressure, we can easily calculate stresses which are in barrel.

First we calculate the force on the inner surface of the barrel for a given length L.

Force= Pressure*PI*ID*L

The stress in the barrel is calculated:

Stress= Force/Area(single wall section)

The area of a singel wall section = (OD -ID)*L/2

Since Stress = Force/Area(single wall section) then by substitution

Stress = (Pressure*PI*ID*L)/((OD-ID)*L/2) which reduces to:

Stress = 2 Pressure*PI/(OD/ID -1)

My 25-06 is a minumum 7/8" at least8' past the lands. So I am going to use this as a measure of the outside diameter of the barrel. The inside diameter is .257. So at peak pressure(51,000 psi) the stress in my 25-06 barrel is 133,258 psi.

Now lets calculate the stress in the barrel ofa 25,000 psi load in my 50 cal muzzleloader. Just past the breech plug, in the area where the powder charge is the diameter of my 50 cal inline is 1". The inside diameter is .510 (I used groove diameter on both rifles). So at peak pressure (25,000 psi) the stress in my 50 cal ML barrel is 163,490 psi.

Please, please, take a moment and reflect on that. Considering that with a Muzzleloader there is always the potential to double load, short seat, and so on. Wouldn't you think it would be a whole lot better to have some room to play with regarding stresses? The 25-06 with its special smokeless steel is literally stressed less than the ML barrel with a magnum load.

A big bore doesn't carry pressure in terms of the stresses in the barrel as well without going really heavy and thick on the barrel. Even a 50-140 Sharps smokeless load is never to exceed 27500 psi. A Sharps is much heavier with a much greater wall thickness, especially at the breech. It is no wonder Hogdon Powder company PROHIBITS the use of more than two pellets in any 50 cal muzzleloader. This is not to say, as T7 so eloquently put it, everything is OK as long as nothing goes wrong. But for any of you out there that are under the impression thatML barrels have a "BUNCH OF SAFETY FACTOR BUILT IN", think again. Without knowing the actual minimum strengths of the steels used, I can notbegin to calculate how much safety factor is there. But it should be clear, if something does go wrong, the stress in the barrel can climb to twice the stress of a high powered rifle barrel.

The good news is this, if you reduce your charges so that the maximum pressure is say, 12500 psi, then you cut the stress in half to 81745 psi which is manageable and a fraction of smokeless stresses.

Now U.C. has suggested that I have some kind of selfish alterior motiveand Wolfhound has been trying to trip these threads up. If I have offended anyone with the way I have responded to them, I apologize. I am completely sincere when I say that I feel this is good information, information that we can all use to help us be more safe. Even should one choose to use magnum loads, at least he does it with the knowledge that there is little safety factor built into his muzzleloader. He must never short seat, never double load, and always break-in a new rifle on lighter loads first.

I sincerely hope that all this rhetoric can be dismissed with, so we can get to the bottom of all these safety questions. If we are going to say a Spanish barrel is "soft", lets know what its strengths actually are. If we are going to say that White isstronger than a Knight or a BPI, then lets know why andby how much. Too many have just spouted off seeminglyundocumented andpotentially libelous things. I have always found it curious that they arecommonly followed by recommendations of where to spend one'smoney and how to"add multiply and divide" and, of course, I am not talking about me.

Happy Hunting, Phil